Disulfide-Directed Multicyclic Peptides for Chimeric Antigen Receptors Targeting Solid Tumors.

Area of Science:

• Immunotherapy
• Oncology
• Molecular Biology

Background:

• Chimeric antigen receptor (CAR) T cell therapy faces challenges in solid tumors, including "on-target, off-tumor" toxicity and cytokine release syndrome (CRS).
• Current CAR T cell designs often lack specificity, leading to adverse effects.
• Novel antigen-recognition domains are needed to improve CAR T cell safety and efficacy.

Purpose of the Study:

• To develop a new class of CARs utilizing disulfide-directed multicyclic peptides (DDMPs) as antigen-recognition domains.
• To evaluate the safety and efficacy of DDMP-based CAR T cells in targeting solid tumors expressing HER2 and TROP2.
• To investigate the mechanisms underlying the improved safety profile of DDMP-CAR T cells.

Main Methods:

• Engineered CAR T cells employing DDMPs targeting tumor-associated antigens HER2 and TROP2.
• In vitro and in vivo assays to assess antigen density-dependent cytotoxicity.
• Measurement of cytokine secretion and T cell signaling pathway engagement.
• Comparison with conventional single-chain variable fragment (scFv)-based CAR T cells.

Main Results:

• DDMP-CAR T cells demonstrated antigen density-dependent cytotoxicity, effectively eliminating high-expressing tumor cells while sparing low-expressing cells.
• Reduced secretion of pro-inflammatory cytokines was observed, indicating a lower risk of CRS.
• DDMP-CAR T cells showed distinct T cell signaling and reduced cell avidity compared to scFv-CAR T cells.
• Mitigation of "on-target, off-tumor" toxicity was achieved.

Conclusions:

• DDMP-based CARs represent a promising strategy for developing safer and more effective CAR T cell therapies for solid tumors.
• The antigen density-gated killing and restrained cytokine release offer a significant safety advantage.
• This novel CAR framework has the potential to overcome current limitations in solid tumor immunotherapy.